Interrupt
also: IRQ · ISR · interrupt service routine
A hardware signal that pauses the processor's current work to handle an urgent event right away, such as a button press, timer tick or arriving data.
Instead of constantly checking (polling) whether something has happened, firmware can let the hardware raise an interrupt. The processor saves its place, runs a short interrupt service routine, then resumes. Interrupts are how microcontrollers react within microseconds to encoder pulses, incoming bytes, timer ticks and fault signals, while sleeping the rest of the time to save power.
Where it bites: interrupt handlers must be short, because other work waits while they run. Data shared between interrupts and the main code causes some of the hardest bugs to reproduce: rare, timing-dependent glitches that show up only in the field. Priority choices decide which events can delay which others.
Founder takeaway
Ask which events are interrupt-driven, how long handlers take in the worst case, and how shared data is protected.
sources
engineer review pending